The state's key witness has testified in the treason trial of Zimbabwe's main opposition leader. Ari Ben Menashe, a controversial Canadian political consultant, said he was asked to arrange the killing of President Robert Mugabe.

Mr. Ben Menashe took the stand on the second day of the treason trial. He runs a political consulting firm based in Montreal and claims to be a former Israeli army intelligence officer.

He testified that he met repeatedly with Zimbabwean opposition leader Morgan Tsvangirai and two other senior officials from his party, the Movement for Democratic Change.

In those meetings, Mr. Ben Menashe claims the Movement for Democratic Change officials offered him a large amount of money to kill President Mugabe and make it look like an accident. He claims Mr. Tsvangirai told him that President Mugabe "will not leave office unless he is taken away in a coffin."

Mr. Tsvangirai and his two co-defendants, Movement for Democratic Change Secretary General Welshman Ncube and member of parliament Renson Gasela, say they are innocent. They are accused of plotting a coup as well as the assassination of President Mugabe, but they say the charges are politically motivated. They claim they have been framed.

The state's case is likely to hinge on a secretly recorded videotape that shows the three officials meeting with Mr. Ben Menashe and, the prosecution claims, discussing the "elimination" of Mr. Mugabe. Defense lawyers say the tape has been heavily edited to make their clients look guilty.

The independent Media Monitoring Project in Zimbabwe agrees that the tape has been altered. A copy of the tape broadcast on Zimbabwean national television showed a timestamp, which jumped back and forth repeatedly, indicating it has been edited from the original version.

Since making the videotape, Mr. Ben Menashe's Montreal-based consulting firm, Dickens and Madson, has been given a lucrative contract to polish the international image of the Zimbabwean government.

The head of the defense legal team, George Bizos, argues that the government contract makes Mr. Ben Menashe an unreliable witness. Mr. Bizos is a prominent South African human rights lawyer who defended Nelson Mandela when he stood trial for treason in the 1960s.

Meanwhile, two Zimbabwean journalists who were arrested Monday outside the courthouse have been released. After spending more than 24 hours in jail, freelance reporter Ish Mafundikwa and local newspaper reporter Pedzesai Ruhanya were freed without being charged with any crime.

Their lawyer says the attorney general ordered their release after considering the evidence against them.

Police arrested the two men during the chaos that erupted as the treason trial began. Authorities tried to bar independent journalists, lawyers, and several Western diplomats from the courtroom, and then fired tear gas at protesters who massed outside the courthouse.

The judge later ordered the courtroom opened to the public. The trial is expected to continue for about three weeks.